CodeHighlighter class needs examples for better understandability

**Your Godot version:**
4.3.stable

**Issue description:**
The CodeHighlighter class has fields that are hard to understand for users, those being the following: [color_regions](https://docs.godotengine.org/en/stable/classes/class_codehighlighter.html#class-codehighlighter-property-color-regions), [keyword_colors](https://docs.godotengine.org/en/stable/classes/class_codehighlighter.html#class-codehighlighter-property-keyword-colors), [member_keyword_colors](https://docs.godotengine.org/en/stable/classes/class_codehighlighter.html#class-codehighlighter-property-member-keyword-colors), They can be improved by providing examples of how these fields are used.

**URL to the documentation page (if already existing):**
https://docs.godotengine.org/en/stable/classes/class_codehighlighter.html